The background of the invention is given in great detail in the above identified applications.
A schematic drawing of the prior art fabrication procedure for a monolithic array of semiconductor laser diodes is shown in FIG. 1. A substrate 2 of n-type GaAs material has a number of layers grown epitaxially. The important cladding layers 6 of n-type AlGaAs and 7 of p-type AlGaAs surround an active layer 4 which normally has a lower bandgap than the cladding layers and may be composed of many layers of AlGaAs, GaAs, InGaAs, or other III-V semiconductor compounds. A layer of exposed and developed photoresist 8 is shown with openings 9 etched in the photoresist. Step b of the prior art procedure uses an etching step to etch vee grooves in the cladding layer 7, generally through the active layer 4 and into the other cladding layer 6. A blanket layer of insulating material 12 such as SiO2 is then deposited on the substrate. This step generally requires heating the wafer which can increase the defects generated by heating and cooling the many layers of different material. Another layer of photoresist is then deposited on the wafer, and is exposed and developed in an expensive alignment procedure to give the photoresist portions 14 covering the vee grooves 10. The SiO2 is then etched away from the areas between the vee grooves 10, the photoresist is stripped, and blanket metalization layers 18 and 20 are deposited over the front side and the back side of the wafer. The remaining oxide isolates each laser diode from its neighbor. In contrast, the fabrication of a monolithic array of semiconductor laser diodes using the method of U.S. application Ser. No. 08/339,811 filed Nov. 15, 1994 (Now U.S. pat. No. 5,559,058) cited above is shown in FIG. 2, where pulsed anodic oxidization is used to produce trenches 22 covered with native oxide 24, saving the expensive lithography step of the prior art.